A game system is per se known that is provided with a play input apparatus that is used for inputting play actions, and that provides a music game in which the execution timings at which play actions are to be executed are guided in accordance with the rhythm of a musical piece that is selected from among a musical piece group. Moreover, with a game system of this type, in some cases, a simulated guitar may be employed as a guitar type input device, and the operation of a picking blade of this simulated guitar may be employed as a play action. For example, a game system is per se known (for example, refer to Patent Document #1) that guides appropriate operational timings by shifting a notes bar so that the notes bar that corresponds to an operational timing on the picking blade coincides with a reference line that corresponds to the present time instant, at the present time instant.